The Pros and Cons of Web Programming Ferenc Vajda Computer and Automation Research Institute of the Hungarian Academy of Sciences and the Technical University of Budapest Budapest, P.O. Box 63, H- 15 18 Hungary

the right language and environment for the job. It means not only to find a solution which fits the job but it must fit to the implementer as well.

Abstract The paper evaluates the most important Web programming languages (i.e. Perl, Unix Shell, C and C++, Java, Eiffel, Scripts). After ovewiewing the significant features, the advantages and limitations are compared. The suitability of different programming means for specific applications is also considered and discussed.

2. Comparison of Web programming means There are many aspects, which should be considered. Web servers are based on the well-known client server principle and system architecture. The mechanism for safely transporting data from a client (e.g. a browser like Netscape Navigator) to a server is called Common Gateway Interface (CGI). [I] Client requests are handled by the server using socalled daemon programs. The CGI is the most common approach to client-initiated programs which uses standardised methods and nearly all Web servers support it. On the other hand client-side programming uses applications that run in the client i.e. the browser. (Typical client-side programming languages are JavaScript and VBSscript, see later). When dynamic elements are included in a Web page a method called Sewer-Side Includes (SSI) is ideal. A third mean is the Application Programmer s Interface (API) which is proprietary method based on a set of programming commands designed to run under a given server (as the Microsoft’s 11s). The advantage of developing programs using API is that we can get faster solution than a CGI version but an important disadvantage is that M I S are not standardised. A promising new version of the TCPiIP protocol is the Inter-ORB Protocol (IIOP) which is part of the Common Object Broker Architecture (CORBA). The CORBA specification [13] describes IIOP as the TCPiIP implementation of GIOP, the General Inter-ORB Protocol. GIOP defines a network protocol-independent set of messages, formats and data encoding that all Object Request Brokers (ORBS) must follow when communicating with each other. Before discussing the advantages and disadvantages of the most important programming languages, a number of important categories are briefly summarised.

“There does not now, nor will there ever, exist a programming language in which it is least bit hard to write bad programs” Flon’s Axiom

1. Introduction The World Wide Web or the Web for short comes to life when it is interactive. There are many ways to have some form of interactivity but most cases it involves programming of some type to process the user’s request and provide the information helshe has asked for. Though the Web is only a few years old, it has matured at a very fast pace. Today, people expect more from sites that support Web pages, including text, graphics and other multimedia content. People can surf on the Web using a Web browser program, such as Microsoft Internet Explorer or Netscape Navigator. There are different categories or application areas for Web programming. Usually the main goal of Web programming is to create dynamic Web pages, which interact with the user in some way. A typical application of this category is processing user forms. Other Web programs do not interact with user directly. These programs are called back-end programs. A typical program of this kind is one that analyses the activity of a site. There are many different application environments and programming means that can be used for Web programming. Each language in wide use for applications has advantages and disadvantages. A systematic comparison could help a Web programmer in choosing

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- Language type: Procedural vs. Object-Oriented (00). A part procedural, part object oriented language is called Object-based language. Examples of procedural languages used on the Web include Unix Shell script, C, Perl, examples of object-oriented languages are C++ and Java while examples of object-based languages used include VBScript and JavaScript. - Compilation method: Interpreted vs. Compiled. (It is well known that compiled applications are generally considered more difficult to write but they tend to be faster. On the other hand, an interpreted program can be written and tested interactively but they usually run slower.) Examples of compiled languages used on the Web are C and Java while Perl, JavaScript, WBScript and Unix Shell script are included in the interpreted category. - Data Typing: Strong vs. Loose. Strong data typing which requires the programmer to define the type used helps to improve program performance and reliability but requires more effort from the programmer. Loose (weak) data typing, on the other hand, provides automatic detection of the type of data being used but can cause programming errors when used carelessly and sometimes the finished program is less efficient. Examples of programming languages require strong data typing are C, C++ and Java while JavaScript, VBScript, Unix Shell scripts and Perl belong to the loose (weak) data-typing category. It is hard to compare programming languages. In essence it can be said that it is not the programming languages but the programmers can be classified as good or bad. For choosing the language of interest the following general criteria can be considered: 1. Criteria of the language itself. It includes - Programming efficiency (maintainability, expressiveness, writability, readability) - Simplicity (generality, orthogonality, uniformity) - Extensibility - Intended purpose 2. Compiler is also a very important factor when choosing programming languages. The compiler criteria include: - Efficiency (translation, execution, optimization) - Reliability - Portability (machine-independence) 3. The available support tools are also very important. As: - Compiler - Debugger - Documentation - Libraries - Integrated development environment

To give a more comprehensive basis for comparison, selected features of the most commonly used Web programming languages are summarised.

3.1. Perl Perl [2] [3] [4] is one of the most widely used language for Web applications. Originally it was developed for the Unix operating system but now it is available on all major operating systems including Windows, Macintosh, DOS, and OS/2. Main reasons of Perl’s popularity: - Good string management capabilities - Very many free programs and scripts available on the Internet - Interpreted language (nearly identical interpreter on all platform) -Easy to learn (steep learning curve)

3.2. Unix Shell On Unix servers it is natural using a Shell language to program Web-based applications. Unix Shells (the three most important ones are the sh, Kom and csh versions) provide for control via Shell scripts (Scripts are processed by the Unix operating system by a text-based commandline processor). The most common Unix Shell used on Web servers is a (public domain) variant of sh called bash. Someone can assign variables, manipulate text, compare values, perform loops and activate programs on the server. (Functions from built-in Unix commands and utilities can also be used). There are negative features as well: - Slow speed (especially at complex programs) - Strict syntax - Programming style is moving to other environments therefore the available free support (e.g. example script) is less on the Web. For quick and not very sophisticated application a Shell program is a perfect way because it is easy - to learn - to write - to test (even interactively).

3.3. C and C++ C [5] is widely available and can be found on every modern platforms (Unix, Windows, MS DOS, 0512,

Macintosh). It is an ANSI standard language, which means almost platform-independent code. C is favoured because it offers great

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- speed - power

3.5. Visual Basic (VB)

-flexibility -portability. C provides a large library of routines for a variety of tasks (e.g. text manipulation, arithmetic, files reading and writing). Of central importance is the C compiler, but different commercial and non-commercial compilers are available. C++, the language family object-oriented offspring has all the advantages and features of object oriented languages but it is more difficult to write programs in C++ than in C. To support program development some C++ variants as Visual C++ and Borland C++ provide an IDE (Integrated Development Environment) that integrates the compiler with an editor, an environment to compile a program directly from the editing.

Microsoft Visual Basic also can create Web-based applications. Its strength is in creating Window-based user interfaces, like dialogue boxes, quickly. Using native code compilation and visual creation of open ActiveX components (canned, industry standard elements) it can create high-performance applications. With up-to-date add-in tools VB applications can be converted to Java. (Note that while VBScript has “borrowed” the VB initials it lacks many of Visual Basic powerful features, e.g. file manipulation commands).

3.6. Eiffel Eiffel is a pure object oriented language. It also includes a comprehensive approach to software construction: a method and an environment (ISE Eiffel). The ISE Eiffel compiler generates an internal form (bytecode) which can be interpreted directly but it can also be translated into other forms (e.g. the bytecode can be optimized and translated into C to take advantage of the presence of a C compiler).

3.4. Java Java [6] is a network-centric computing platform. There are two forms of Java applications. Java applets [7][8] are small programs. They are embedded in Web pages and downloaded to and run within the browser on a client machine. (Similarly, Active X components are applets written for special platforms). In contrast, Java applications are full-fledged programs installed locally on a machine. Java is usually referred as a portable or cross-platform language. This key feature is based on two key components, i.e. bytecodes and the Java VM (Virtual Machine). VM is a software-based machine i.e. just a software program which has been ported to nearly all of the predominant computing platforms in use today. The VM processes bytecodes, a platform-independent instruction set. Bytecode is translated, - on-the-fly - into the platform-specific machine code instructions executed by the host machine. This is the price of the portability and therefore Java programs run more slowly than programs compiled directly to machine code. However, because the bytecodes were designed for efficient translation to machine code, Java is significantly faster than other interpreted languages. (Recently several socalled just-in time compilers are available to compile the bytecode to platform-specific machine code). Java is an object-oriented language that is syntactically similar to C++ and provides the language support of usual objectoriented languages. The Java Chip chipset is an alternative implementation of the virtual machine to allow Java programs to be run in small systems such as electronic devices. Typical examples are the Personal Java and Embedded Java platforms for consumer devices use in every day life (e.g. set-top boxes to connect to and download contents).

3.7. Scripts Scripts are small programs that interact with the browser and the HTML content of a page (In HTML the SCRIPT tag is used to enclose mnable script, which is interpreted as executable code). JavaScript [9] and VBScript [lo], the two main solutions are strictly similar and supported by the Netscape Navigator and the Internet Explorer, respectively. Scripts can be used for - tailoring pages - mailing interactive pages - computer-aided instructions - special effects. JavaScript is based largely on C syntax while VBScript is based largely on the syntax of Visual Basic. Both are object-based and interpreted at execution. Objects (e.g. a document) are composed of so called properties, which are handled by so called methods. [9][10]. On the Web very many script repositories [ 111 [ 121 can be found where countless useful programs and scripts can be downloaded mainly either as fveeware or shareware. Different programming languages can be combined to take advantage of the best each can offer.

4. Comparison It is impossible to find or define a single comparison structure for comparing Web programming languages.

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Advantages Text manipulation (exceptional) File management (exceptional) Compact code (for complex operations) CGI scripting (easy) Data type management (convenient)

Disadvantages Syntax (overly flexible) Privacy (unenforced) Exception mechanism (no built-in toy-catch-final 1 Remote code execution (only via Penguin)

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4.2. Another possible consideration at comparison is the general aspects of the user. The data of Table 2 are based on this view.

C : good F : none A : excellent D : moderate B : very good 4.3. It is worthwhile to compare the main features of Object-Oriented languages (Table 3).

In of Object-Orien ?d(00)languages C++ statically but support for “casts” compiled technology

Multiple inheritance Object orientation Openness and interoperability

multiple but problematic hybrid good with C

Java mostly statically but dynamic at generic structures interpretation and “on-the-fly’’ compilation

Combination of interpretation and compilation

historically interpreterbased, partial compilation at current

single with multiple

- interface facility Pure native methods

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Simplic&: combination of the simplicity, regular Y and brevity of the syntax. Pedagogic support: availability and quality of support resources. Cross curriculum: suitability of the language for use in different areas of the curriculum. Learning curve: amount of syntactic overhiead involved in producing an initial artifact.

4.4. Languages - - can be evaluated based on pedagogic suitability criteria, too. Without really judging the languages based on this kind of criteria here we consider only a few possible point of views. Stability and standard: existence of‘ an ANSI andor IS0 language standard and degree of not changing.

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Conceptual expressability: simplicity and regularity of the cognitive connections between syntax and semantics. Hybrid or pure: support both proceduralhmperative and object oriented styles of development or just for object oriented style.

4.5. Languages can be judged based on the suitability to different tasks (Table 4)

Database search (small)

isit counter (graphic) A : excellent

C : good

B : very good

The usual programming point-of views also should be considered, i. e. - Execution speed (compiled language vs. interpreted language) - Ease of programming (learning curve and matching complexity of language and task) - Support (Built-in integrated support "S. third-party libraries)

D : moderate

[5] Mark Felton: CCI: Internet Programming with C and C++, Prentice Hall, 1997 [61 Java; http:i/l92.147.157.5 1:8000/galaxy/ [7] David Culbrausen et al.: Creating Web Applets With Java, S a m Publishing, 1996 [8] Java Applets, http://www.javasoft.comiapplets/ [9] Jason J. Manger: JavaScript Essential, Osborne McCrawHill, 1996 [IO] Christopher J. Goddard et al.: VBscript Master's Handbook, Prima Publishing, 1996 [ 1 I] Central Script Repository, http://www.selah.neticgi.html/ [ 121 Yahoo! Internet-related pages,

5. Conclusions Perhaps the largest obstacle facing a Web programmer is choosing the right language for the job. Not only the language must fit the job but it also must fit the programmer. We have reviewed the major language choices available to Web programmers. The strength and weaknesses of these languages, the jobs they are best suited for were considered. The pros and cons of Web programming were discussed comparing the languages based on the criteria of the general aspects, user's points of views, pedagogic suitability. The Web represents a new medium of information exchange based on globally networked, distributed and linked information space. The Web has an enormous impact on software development and distributions as well. However, these topics are beyond the scope of this paper.

http://www.yahoo.com/Computers_and_Intemet/Intemet/World -Wi de-Web/ [ 131 CORBA 2. I Specification

http://www.omg.org/corbdcorbiisp. hm/

References [ l ] William E. Weinman: The CGI Book, New Riders Publishing, 1996 [2] Eric F. Johnson: Cross-platform Perl, IDG Books,1996 [3] Thomas Boutell: CCI Programming in C & Ped, AddisonWesley Pub. I996 [4] Achive Perl CGI Scripts, http://www.middlebury.edu/-otisgi

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